Conventionally, an endoscope has been widely used in a medical field, an industrial field, and the like. For example, in the medical field, an endoscope is used when various treatments are performed on a region of body cavity in a living body, tissues, or the like, which are diseased parts.
A bending portion of an endoscope is provided with a mechanism for directing a distal end portion of the bending portion to a desired region by a bending action of the bending portion in order for an operator to surely perform various treatments when performing various treatments on the diseased part with the endoscope. Such an endoscope having the above-described mechanism is proposed in Japanese Unexamined Patent Application Publication No. 2003-38418, for example.
The bending portion of the endoscope proposed in the Japanese Unexamined Patent Application Publication No. 2003-38418 has a configuration in which a plurality of bending pieces are provided, and the shape of the bending portion is changed by advancing and retreating a bending wire with the operation of a bending portion operation knob provided in an operation portion of the endoscope.
In order to realize the configuration, a bending mechanism configured of a motor, the bending pieces, the bending wire, and the like, is required to be provided to an operation portion, an insertion portion, and the bending portion. However, providing the bending mechanism to the endoscope leads to an increase in weight of the endoscope itself and as a result, physical burden of an operator increases when performing a treatment by using the endoscope for many hours on end.
On the other hand, U.S. patent application publication No. 2003/0006669, for example, discloses a configuration in which a roll-shaped conductive polymer member is formed by winding in a cylindrical shape a thin plate-like conductive polymer having electrodes on both opposed surfaces thereof, and the part on which electrodes are provided can be bent by extending and contracting in a thickness direction with application of voltage to the electrodes opposed to each other.
In addition, the publication discloses a conductive polymer actuator ensuring a shape recovery function by providing a coil-shaped spring inside of the roll-shaped conductive polymer member.
The conductive polymer actuator has a possibility of reducing the weight of the bending mechanism and improving operability when utilized in a bending portion of an endoscope.
The operability is enhanced if responsiveness can be further improved.
The present invention has been made in view of the above-described points and an object of the present invention is to provide an endoscope capable of improving operability for changing a shape of a bending portion as well as improving responsiveness.